To add on to the comment CityBus made:
I haven't read around to see if anyone is working on this: students and children. I find myself giving out the same three tickets over and over (Regular, Short Trip, and Day Pass - mentally renamed them to make it easier to remember). I would like to give out the student-discount tickets as well. I also noticed that there are other tickets that the ticket printer on the D92 can print out. For example, there is a 15DM ticket, don't know what fare type it is (I don't speak German), that I would love to sell so the ticket gains increases faster.